Ball valve for fluids with seats comprising laminated rings

Abstract

Ball valve for fluids, with sealing seat comprising rings, disposed between the spherical surface of the valve and the interior of the valve body, composed of rings formed of superimposed layers of plates of graphite alternating with plates of stainless steel sheet, the whole being contained in a casing of metal sheet covering the outer sides of the seat, except the one in contact with the spherical sealing surface.

We claim: 
     
       1. A valve comprising: a valve housing provided with a flow passage, said housing comprising upstream and downstream parts spaced apart along said passage, each of said parts formed with: a respective inner annular wall delimiting said passage, and   a respective annular end face, said annular end face extending radially outwardly from the respective inner wall;     a valve ball received in said housing along said passage and rotatable about an axis transverse to said flow passage between an open position and a closed position of said valve, said valve ball being formed with: an inner bore provided with an inner annular surface flush with said annular inner walls of said flanges and forming a continuous peripheral wall of said passage in said open position of said valve, and   an outer spherical surface extending outwardly of said inner annular walls of said flange and forming respective widening outwardly gaps with said end faces; and     annular seats mounted in said gaps, each of said seats comprising:   a respective metal casing having a side juxtaposed with said end face of the respective flange,   a plurality of layers of graphite plates, and   a plurality of layers of hard metal plates alternating with said layers of graphite plates, said pluralities of juxtaposed plates extending transversely to said passage and forming a respective sealing surface shaped complementary to and in contact with said spherical surface.   
     
     
       2. The valve defined in claim 1 wherein said side of the casing juxtaposed with the respective end face is covered with a layer of pure graphite having a thickness from 0.5 to 1.5 mm. 
     
     
       3. The valve defined in claim 1 wherein said sealing surface is formed by a straight line generatrix rotated about the axis along a closed path, so that respective seats and the valve ball contact one another along a respective continuous circular line.